cobiella y vasconcelos



Jan. 4, 1927. v 1,613,221

P. COBIELLA Y VASCONCELOS DRAWI NG IN STRUMENT Filed Feb.' 9, 1924" [N VENT 0R.

Patented Jan. 4, 1927.

lApplication.filed February 9, 1924. Serial No. 6221.692?.

This invention relates to an instrument or apparatus constructed to effect 1n a practical and simple way the" operation for 'dividing the ciiciunfei'ence in 'al given number` ofequal parts, and to inscribeand circumscribe polygons' on the circumference.

`ILleret'ofore in order to resolve the problems ofthe kind. of .elementary geometry, itl

has been`necessary to follow v'certaine rules and draw certain sketches, which are in some cases complicated, 'and therefore, 'cannot easily beretained' in the memory. 'Ilo overconiethi-s inconvenience VI1ha`v"e"`devised the present invention, which has for its object to provide an instrument by means of which a simple operation enables the practical solution of said problems, with great economy of time and labor.

lVith the above object in view, the invention consists in the novel construction, combination and arrangements of parts hereinafter fully described, illustrated in the accompanying drawing and specifically set forth in the claim.

The invention is described in relation with the figures of the drawing, in which Figure 1 is a top plan View of the instrument embodying the invention; Figure 2 is a side elevation view of the same; Figure 3 is a longitudinal section of the instrument shown in Figure 1; and Figure 4 shows in an enlarged scale a detailed view of a part of the instrument.

Like characters of reference indicate like parts in the several views.

1 is a plate in the form of a sector, which presents on its upper side a plurality of divisions equally spaced and marked with the numbers O, 10, 20, etc., up to 120. Said divisions correspond to the 360 degrees in which the circle is divided, and therefore,` as the sector covers only 120, the total size of same is equivalent to the third part of a complete circle. Near the border or edge of the sector, there is another plurality of divisions irregularly spaced and marked with the numbers 3, 4, 5, etc., to 12.

From the central portion of the sector, that is, from the vertex -of the sector, an arm 2 projects, provided with an extension arm 3 which has a downwardly projecting needle 4 in its free end. The arm 2 and the extension 3. are articulated at 5, permitting the extension in this manner to be folded upon the arm 2, to decrease the total length of the instrument, in order that it may set conveniently in any kind of a drawlng instrument- `case.

In a hole provided on the vertex of the i sectory andprojecting downward, a conical piece 6 is threaded, and the upper end'of said piece forms a stem 7, which projects upward from the sector. On said stem an arm 8 is mounted, in such a' manner that it will turn freely around the stem as though on a shaft. In the stem 7a knurled knob 9 is threaded, which serves as a top or butt` in Order to out 4ofthe stem, andat the same time to hold the instrument when it is in use. u

A branch of the arm 8 extends over the sector and presents an extension 10 articulated by the hinge 11, and the other branch extends outwardly of the sector. A slide 12 is mounted on the latter branch so that it may be moved longitudinally. A leg 13 projects downward from the lower side of the slide. The leg 13 is formed to receive a small bar of crayon, 14, which will be held in place firmly by means of the screw 15. The leg 18 is properly inclined in order that the point of the crayon 14 may be placed very near to the point of the conical piece 6 when in use.

The branch of the arm 8 which is extended over the sector 1 and the extension arm 10, are provided with the pins 15 and 16, which engage respectively with the holes 17 and 18 provided on the upper side of the sector, in order to fix both the arm and the extension in the convenient and adequate position.

When the instrument is to be used a prevent` the arm from comingl straight line is first traced from the center of the circumference as a radius, prolonging it beyond the circumference, if it is necessary. Then the arm 8 is rotated on the stem 7 to the desired position until the pins 15 or 16 come in engagement with the corresponding holes, in accordance to the number of parts in which the circumference must be divided. Now the point of the conical piece 6 is set on the center of the circumference and the needle 4 is fixed on its place over the straight line. The slide 12 is then moved on the other branch of the arm 8, tracing a line with the point of the crayon 14, fixed on the leg 13. Said operation will give the first division of the circumference. Now the needle 4 isbrought in place over the latter `line, maintaining the point of the conical plece 6 on the center of the circumference, and another line is drawn with the crayon 14. The operation is repeated successively'until the division is accomplished. v

In the Figure 1 the instrument is fitted to divide the circumference into 6 equal parts. If it is desired to make another division, as per example, 5-or 7 parts, then the extension armkmust be placed in the corresponding mar It is obvious that minor changes may be Vmade in the form and construction of this invention Without departing from the material principles thereof. it is .not therefore desired to conine the invention to the exact form herein shown and described, but it is wished to include all such as properly come Within the scope of the appended claim.

Having thus described the invention, What is claimed as new, is

An' instrument of the kind described, comprising a plate of sector form, the upper surface of the plate being formed with division lines to indicate degrees of a circle, the sector plate being formed with openings with which said lines coincide, the arcuate edge of the sector being provided with division lines, said sector plate being formed with holes with which said last named division lines coincide, a sectional arm including a part rigid With the sector plate and projecting therebeyond and a secondpart having hinged connection with the rigid part, a point carried by said hinged part of the arm, a bar rotatable about the center of curvature of the arcuate edge of the sector, that portion of the bar overlying the sector being formed with a movable extension, means whereby the bar or its extension may be engaged With any one of the holes in the sector, and a marker adjustable on that portion of the bar beyond the sector.

In testimony whereof I affix my signature.

POEMA COBlELLA y VASCONCELOS. 

